APOL6 (apolipoprotein L6) is a BH3-only pro-apoptotic member of the Bcl-2 family that regulates cell death pathways and immune responses. The protein functions as a mitochondria-mediated apoptosis inducer, releasing cytochrome c and activating caspases-8 and -9 in cancer cells 1. APOL6 operates through multiple mechanisms including binding to anti-apoptotic Bcl-XL proteins, promoting reactive oxygen species generation, and blocking Beclin 1-dependent autophagy 2. The protein is regulated by STAT1 and interacts with ACSL4 to mediate ferroptosis, an immunogenic form of cell death 3. In disease contexts, APOL6 shows significant clinical relevance as a biomarker for cancer immunotherapy efficacy. High APOL6 expression correlates with improved response rates and prolonged survival in multiple tumor immunotherapy cohorts, particularly through induction of immunogenic cell death that enhances antitumor immunity 4. The protein demonstrates diagnostic and prognostic value in hepatocellular carcinoma and serves as a predictor of immune checkpoint inhibitor efficacy in bladder cancer and other malignancies 53. APOL6 expression is associated with immune cell infiltration and chemosensitivity, making it a promising therapeutic target for optimizing cancer immunotherapy 6.